Diaphragm pump



p 23, 1953 F. w. PLEUGER 2,853,015

DIAPHRAGM PUMP Filed Jan. 4, 1956 2- Sheets-Shet 2 /gla /0 INVENTOR M34464 MM JHCM ATTO R N EY$ United States Patent Ofitice 2,853,015 Patented Sept. 23, 1958 2,853,015 DIAPHRAGM PUMP Friedrich Wilhelm Pleuger, Hamburg, Germany Application January 4, 1956, Serial No. 557,382 Claims priority, application Germany January 11, 1955 16 Claims. (Cl. 103-44) This invention relates to diaphragm type pumping equipment, and especially to diaphragm pumps utilizing a hydraulic pressure transfer chamber to transfer reciprocatory motion from a driving means to a working diaphragm. More particularly, the invention relates to diaphragm pumps having a pair of spaced diaphragms, one for actuation by driving means and the other for pumping sullage, for instance oil, upon a riser, the construction involving a piston working in a cylinder located between the two diaphragms and a hydraulic transfer chamber for transferring the motion of the piston to the working or pumping diaphragm.

Certain ditficulties are encountered when various prior diaphragm pumps are used for deep well pumping over protracted periods of time. Thus, when metal diaphragms are used, fatigue phenomena causing changes in the crystalline structure of the metal are likely to occur and result in a reduction in strength and eventually in rupture of the diaphragm. When plastic diaphragms are used, even if they are made of a material having high elasticity, the combination of the mechanical type stresses and the thermal type stresses to which they are subjected in service reduces their pumping life considerably. The thermal stresses referred to are concerned with the relatively high temperatures produced within the material during normal operation. Such temperature build up is aggravated by' the difficulty of removing heat from the iaphragms because of the relatively low thermal conductivity of -such plastic materials. Chemical and structural changes will take place within. the plastic material after operation at relatively high temperature for a prolonged period of time. Such changes impair the elasticity and increase the chance of rupture due to 'the mechanical stresses continuously imposed on the material, especially when such mechanical stress is of relatively high magnitude. The material fatigue phenomena just described are also encountered in the construction of automobile tires.

The reduction of the mechanical type stresses on plastic diaphragms is an important feature of the present invention and makes possible the operation of a diaphragm pump over an exceptionally long time, even through the diaphragm is subjected to thermal type of stresses.

In high speed diaphragm pumps the first problem which must be solved is relieving the diaphragms from pressure. This relieving the diaphragms from pressure can be brought about, for instance, by actuating them by means of a piston which bears the main load. When a hydraulic transfer chamber is interposed between a piston and a diaphragm, difficulty is encountered because of the leakage of oil between the piston and cylinder walls. The volume of liquid in the pressure transfer chamber must be maintained substantially constant. When the leakage is replaced in the ordinary way, that is from a reservoir located somewhere in the housing, difficulties are encountered. In almost all cases the oil reservoir space in the housing is at least partially filled with some gas or air. The oil absorbs some of this gas and, when oil is taken from the reservoir for delivery to the transfer chamber, some gas will pass into the sealed hydraulic space and decrease the effective delivery stroke of the piston by adiabatic compression and expansion.

This undesirable effect is avoided by the: invention by keeping the transfer space filled with oil which is free of gas or air. Such gas-free oil is provided by collecting the leakage oil in a sealed collection recess which is completely free of gas and then delivering the collected leakage oil back into the transfer chamber.

Since the pressure piston of the invention moves between two diaphragms in a completely closed space containing gas-free pressure liquid, the returned pressure liquid is also always free of gas. A change ofthe efficiency of the pump with respect to the delivery capacity is avoided, even if the driving motor is closely associated with the pump at the bottom of a deep well and runs in air or gas. M

The primary object of the invention is the provision of a diaphragm pump in which the working diaphragm is actuated by a piston via a pressure transfer chamber A which is kept filled with hydraulic liquid free of any entrapped gas.

Another object of the invention is the provision of a diaphragm pump having a pair of spaced diaphragms sealing a hydraulic chamber between the two diaphragms, the piston and pressure transfer chamber being located within this hydraulic chamber and the whole structure constituting a closed hydraulic system in which any liquid leaking out of thepressure transfer chamber between the piston and its cylinder will be collected and returned to the transfer chamber.

A further object of the invention is the provision of a diaphragm pump of the kind just described which includes means for automatically returning leaked liquid to the transfer chamber more or less continuously during operation. a

Yet another object of the invention is the provision of a diaphragm pump having a working diaphragm arranged to minimize the tendency for particles of solid matter entrained in the liquid being pumped to settle in the pumping chamber.

Other objects and advantages of the invention will be clear from the following description taken. together with the accompanying drawings in which:

Figure 1 is a vertical sectional view through a pump constructed according to the invention;

Figure 2 is a vertical sectional view on a larger scale than Figure l and showing a second embodiment of the invention having a stepped or differential piston;

Figure 3 is a vertical sectional view on a reduced scale as compared with Figure 2 and showing a third embodiment similar to that of Figure 2 but utilizing a modified driving means;

Figure 4 is a vertical sectional view of a fourth embodiment of the invention similar to that of Figure 3 but utilizing a continuous diaphragm separating the piston from the motor means; and

Figure 5 is a vertical sectional view showing a fifth embodiment having the working diaphragm disposed at an angle to the horizontal.

The piston means interposed .between the two diaphragms of all embodiments can be actuated optionally either by a crank shaft and connecting rod connected directly with the piston or by a cam actuated ram, in either type of drive the motor driven reciprocating means acting to distort the diaphragms toward the working or pumping chamber. In the case of the motor driven ram, it is noted that the return stroke of the piston is provided for by a return spring.

In the embodiment shown in Figure 1 the housing 6 is divided by means of working diaphragm 7 and sealing diaphragm 8 into three main portions, namely, the pump chamber housing 9, the transfer chamber and cylinder housing 10 and the motor means housing 11. The pumping chamber 12 within housing portion 9 has an inlet passage 13 and an outlet passage 14. These passages are. provided with one way check valves (not shown) known in the art, for example of the kind disclosed In the copending application by the inventor herein and Johann Christian Grober, Serial No. 497,628, filed March 29;;

1955, and assigned to the assignee of the present application.

During operation of the pump the working diaphragm 7 is fiexed toward the pumping chamber and the inlet valve is thereby closed, the outlet valve opened and sullage is pumped up the well riser (not shown) abovethe pumping unit. During return of the diaphragm to the lower position, the outlet valve closes, the inletvalve opens and oil or other material being-pumped flows into the pumping chamber from the surrounding strata.

The diaphragms 7 and 8 are mounted in spaced rela-. tion between the pumping chamber and the motor means within housing 11. The diaphragms thus provide a hydraulic chamber between the motor means and pumping chamber which comprises a pressure transfer chamber 15 and cylinder means 16 communicating therewith. T he pressure transfer chamber 15 and cylinder means 16 are completely filled with an incompressible l quid such as oil. A piston 17 is arranged for reciprocation in the cylinder means 16. As shown in Figure the Piston 17 is cup-shaped and includes a spring locat ng boss 18 at the bottom of the cup and aserles of piston rings 19 which provide a substantially fluid tight seal between the iston and cylinder wall. p In order to relieve the worling diaphragm 7 (which is clamped firmly at its edges in the pump housing as at 20), from tension and support it when it IS 1n 1ts rest position, i. e., when the pump is not in use or during the return stroke of the piston 17, there is provided within the transfer chamber a perforated plate or supporting screen 21. This supporting screen 21 is located ad acent the working diaphragm 7 and is preferably provided \vzth a resilient or elastic-plastic coating on the side toward the diaphragm.

Between the perforated plate 21 and the bottom of the cup-shaped piston 17 there is provided a compression spring 22 which urges the piston 17 against the sealing diaphragm 8.

In the form shown in Figure 1 the lower or sealing diaphragm 8 is continuous and is clamped at its edges in the housing as at 23 in the same manner as diaphragm 7.

Reciprocating means or ram 24 is driven by the motor means (shown in Figure 1 as a cam 25 fixed on drive shaft 26 which may be rotated by any suitable drive means such as an electric motor not shown, enclosed within the lower portion of the housing 11. A resilient ring 27 preferably surrounds the upper portion or head 28 of ram 24 in order to avoid injury to the diaphragm 8 when it is struck by the piston 17 at the end of the downward stroke.

As seen in Figure 1 the ram 24 includes a head 28 of slightly larger diameter than the ram but this head is smaller in diameter than the piston 17. Since the ram 24 continuously contacts the lower surface of the diaphragm 8 and the piston 17 is continuously pressed by the compression spring 22 against the upper surface of the diaphragm, there is obtained in each position of operation a surface clamping of the central part of the diaphragm which is important in minimizing the: mechanical stress to which it is subjected.

In the arrangement shown in Figure l, the reciprocatory motion of the ram 24 is transmitted via the diaphragm 8 to the piston 17. Since the space between the upper diaphragm 7 and the lower diaphragm 8 is completely filled with gas-free oil, the piston 17 transmits its motion to the liquid contained above it so that the upper diaphragm 7 is raised and the volume of the pumping chamber 12 is decreased so that a portion of the liquid in the pumping chamber is forced out through the displace by means of the force of spring 22 as the cam 26 turns so that the ram 24 may move downwardly.

Upon each compression or conveying stroke of the piston 17, a small quantity of the pressure liquid in the transfer chamber 15 will leak downwardly between the cylinder wall and the piston 17 (notwithstanding the presence of the piston rings 19) and thus arrive in the region of the lower diaphragm 8. A liquid collection recess 29 is provided in the wall of the cylinder means adjacent the lower diaphragm and the liquid which leaks downwardly is collected therein. A return conduit 30 interconnects the liquid collection recess 29 and the pressure transfer chamber 15, the return conduit being provided with a one-way check valve 31 which is adapted to permit flow to the transfer chamber and to prevent flow therefrom.

Because of the ditference in area of the face of ram head 28 and'piston 17, the annular liquid collection recess 29 changes in volume during reciprocation of the ram and piston. The volume of annular space 29 is at a minimum when the piston 17 is in the lower or rest position shown in Figure 1, so that upon the return of the piston 17 to this downward position, excess liquid which has leaked into the collection recess 29 will be forced out through the passage 30 and the check valve 31 into the transfer chamber 15. Even though the annular space 29 increases in volume during the upward or operating stroke of the piston 17, liquid cannot be drawn through the outlet passage 30 because of the check valve. This results in a tendency to suck the diaphragm upward and thus minimize the stresses to which it would otherwise be subjected.

During the compression stroke, the piston 17 takes up the main pressure and thus afiords a protection against excessively high pressure on the diaphragm 8. The diaphragm 8 need merely overcome the pressure which results from the admission of the liquid being pumped during the return stroke.

The self-enclosed hydraulic system bounded by the diaphragms 7 and 8 may be filled under vacuum via the filling conduit 32 provided with a plug 33, which conduit is extended through the cylinder wall and into communication with the return conduit 30.

In the embodiment shown in Figure 2 the lower or sealing diaphragm 8a is completely relieved of stress. The diaphragm 8a in'this embodiment is toroidal and is clamped at its outer edge in the housing and at its inner edge in a two-part crosshead 34-34a. The crosshead bushing 35 is firmly supported in the housing. The crosshead 34 is recipro'eated by means of the connecting rod 36 and the drive shaft 37. Instead of the single piston 17 as shown in Figure l, the Embodiment of Fig. ure 2 includes a double or stepped piston arrangement having an upward piston portion 17a and a lower piston portion 17b somewhat smaller in diameter than portion 17a. A screw 38 passes through central apertures in the two pistons 17a and 17b and secures them to the two parts 34 and 34a of the crosshead.

The cylinder is stepped. in a manner corresponding to the two piston portions 17a and 17b to provide a cylinder 16a and a cylinder 16b which are concentric and intercommunicating. The cylinder 16a adjacent the transfer chamber-15 is larger in diameter than the cylinder 16b more remote from the transfer chamber.

The pistons 17a and 17b are provided with piston rings 19a and 19b respectively. The parts arranged above the transfer chamber 15 are essentially the same as those shown in Figure 1 and perform the same function.

During operation of the pump the upper piston 17a advances into the transfer chamber 15 and thus displaces a portion of the liquid filling the chamber which in turn raises or distorts the diaphragm 7. As a result the material being conveyed is forced out of the discharge valve into the well riser. A spring for the return of the stepped piston to the lower position is not necessary in the embodiment of Figure 2 since the piston is connected with the driven crosshead 34 which is positively returned by the crank 36.

The resilient or elastic plastic coating on the diaphragm side of the supporting screen 21 isshown in Figure 2 as 21a.

Liquid collection recess 29q/is provided adjacent the lower diaphragm and a second liquid collection recess 39 is provided in the wall of the upper cylinder, the recess 39 being located in the region of the interconnection between the upper and lower cylinders Return conduit 30a connects both the recess 29a (via the auxiliary passage 40 and auxiliary recess 39b) and the recess 39 with the transfer chamber 15. The one-way valves 31a and 41 are provided to premit flow toward the transfer chamber and to prevent flow in 'the opposite direction. Valve 41 also prevents flow from recess 39 to recesses 29b and 29a. The major portion of the oil which leaks between the upper piston 17a and the cylinder wall is collected in recess 39 and returned to the transfer chamber via the passage 30a in a manner similar to that described in connection with Figure l. A minor portion of the leaked liquid escapes between the lower piston 17b and its cylinder wall and is collected in the recesses 29a and 29b and from there is delivered via thereturn conduit and valve 41 into the upper collection recess 39.

Because of the larger diameter of the upper piston portion 17a, there is a tendency to create a vacuum in the space 39 during upward motion of the two pistons. Hence, a sucking force is applied to empty the recesses 29a and 29b and the passages associated therewith into the recess 39. 0n the next downward stroke of the pistons, the check valve 41 will close and the excess liquid will be delivered through the check valve 31a to the transfer chamber 15. Thus the upper piston acts as a conveying piston while the smaller or lower piston acts as a drainage piston. With suitable dimensioning of the two piston portions 17a and 17b it is possible to obtain a slight vacuum in the collecting recesses 29a and 29b sothat the lower or operating diaphragm 8a is sucked upwardly. It thus results that due to the piston arrangement between the two diaphragms 7 and 8a, a complete release of thediaphragm 8a from stress is achieved.

When the pump is not in operation the liquid in the pressure transfer chamber 15 will leak slowly past the pistons into the lower annular collection recesses so that the latter will fill up with pressure liquid.

If the pump has a very high pressure, which may result from a high liquid column above the pump at the bottom of a deep well, the perforated support or screen 21 affords additional protection for the conveying or working diaphragm 7. This diaphragm can rest upon the screen after the initial portion of the downward motion of the pistons has permitted part of the transfer liquid to move downwardly. In this way the pressure of the column above the diaphragm 7 is never imposed in full upon the diaphragm 8a. v

The closed hydraulic system between the two diaphragms can be filled in vacuum via the filling conduits 32a and 32b having plugs 33a and 33b.

Lubricationof all of the moving parts between the two diaphragms is assured by reason of the circulation of oil from the transfer chamber to the collection recesses and back again.

The lubrication of the crosshead 34 can be effected either by grease in lubricating grooves provided in the bushing 35 or, if the motor means and gearing in the lower portion of the housing 11 operate under oil, in a manner to be described herebelow involving the use of .the diaphragm 8a as a lubricant pump.

In the latter arrangement, the upper portion of the crosshead 34 is surrounded by a lubrication recess 50 of the oil will escape ance may be returned to the reservoir through a return passage 52. The passage for oil between the piston and cylinder and passage 52 together comprise return passage means for oil flow from the lubrication recess to the reservoir. 7

The mouths ofthe supply conduit and return passage are surrounded by rings of resilient material 53a and 53b respectively in order toprotect the diaphragm.

With the above described arrangement the diaphragm 8a during upward motion of the pistons acts like a pump and draws oil in through valve 51. This oil circulates around the crosshead and discharges out between the crosshead and bushing and also out through the passage 52 as indicated by the arrows 54.

The embodiment shown in Figure 3 is quite similar to that shown in Figure 2 except that the double pistons 17a and 17b are not connected with the drive shaft 37 by means of a connecting rod but rather by a cam 25a and ram 24a generally similar to those shown in Figure l. The double pistons are connected to the reciprocating member 24a by means of a screw 38. In this embodiment, as distinct from that in Figure 1, the lower diaphragm 8a is toroidal in shape rather than continuous.

The return motion of the stepped piston is effected by means of a volute spring 22a, which abuts at one end against the bottom of the screen 21 and at the other end against the top of the upper piston 17a. Because of this spring the conveying capacity of the pump is not dependent solely on the hydrostatic pressure of the liquid column existing over the pump.

The collection of leaked oil in recesses 39 and 29a and the return thereof to the transfer chamber 15 is accomplished in the manner described in connection with Figure 2. It is here noted thatthe section of Figure 3 is at a slightly different location from that of Figure 2 and some parts, therefore, do not show.

The embodiment shown in Figure 4 illustrates a double piston arrangement similar to that shown in Figure 3 but including a continuous lower diaphragm 8, a ram 24 having a head 28, a surrounding resilient ring 27, a cam 25 and a shaft 26 all as shown also in Figure 1. This embodiment has a pressure disc interposed between the lower diaphragm and the lower piston 17b.

The upper and lower pistons 17a and 17b, the volute spring 22a, the upper diaphragm 7 and supporting screen 21, the liquid collection recess 39, the return conduit means 30a having check valves 41 and 31a all perform essentially the same functions as the corresponding parts in the other figures. A collection recess 290 similar to 29a of Figure 2 is arranged to accommodate the disc 60.

The embodiment shown in Figure 5 is also driven by a cam acts directly on the lower end of the lower or drainage piston 17b. The return of the liquid takes place via the conduit 30a in the manner above described and the two pistons are urged toward their lower position by means of avolute spring 22b which, in this embodiment, abuts against a flange 61 protruding from the wall of the transfer chamber 15 and against the top of the upper piston 17a.

In the embodiment of Figure 5 there is a substantial difference in the arrangement of the conveying or working diaphragm 7a which is now disposed at an angle to the horizontal. The perforated plate or screen 21a is likewise tilted in order to serve as a relief support for the diaphragm 7a. The pumping chamber 12a is arranged above the diaphragm 7a so that the inlet. passage 13a provided with a check valve 62 is adjacent the highest point on the diaphragm while the outlet passage 14a having outlet check valve 63 is arranged adjacent the lowest point on the diaphragm 7a. The cross section of the discharge passage 14a is hydrodynamically developed to provide a progressively increasing velocity of flow of liquid leaving the pumping chamber 12a.

The embodiment of Figure is particularly advantageous when pumping liquids having a substantial portion of entrained solid contaminant. w The intake, outlet and pumping chamber are arranged so as to minimize the tendency for solid particles to settle in the pumping chamber or outlet passage. The working diaphragm 7a in the inclined position (in combination with the inlet and outlet arrangement shown) constitutes, in effect, a shaking chute. The inlet valve, shown here as a flap valve, permits the impurities to pass through at the highest point of the diaphragm. These impurities then' slide down the oblique diaphragm to the lower-most point at which they are swept out of the discharge passage and carried along into the well riser.

In all of the embodiments shown herein, in order to reducethe thermal stresses imposed on the diaphragms, the motor means housing 11 can be filled with a good heat conductive gas, for instance hydrogen, in order to facilitate removal of heat when dry operation is contemplated, or else with oil when wet operation is contemplated.

I claim:

1. Pumping equipment comprising motor means, a pumping chamber, a pair of flexible diaphragms mounted piston and diaphragm is greater than the area of contact between the ram and diaphragm.

6. Pumping equipment according to claim 5 and further including aring of resilient material surrounding said ram and in contact with said other diaphragm.

7. Pumping equipment comprising motor means, a pumping chamber, a pair of flexible diaphragms mounted in spaced relation between said motor means and pumping chamber, a pressure transfer chamber between said diaphragms, cylinder means between said diaphragms and in communication with the transfer chamber, liquid filling said transfer chamberand cylinder means, one of said diaphragms sealing the pumping chamber from the transfer chamber and the other diaphragm sealing the cylinder means from the motor means, reciprocating means driven by the motor means and operative to distort said other diaphragm toward the pumping chamber,

in spaced relation between said motor means and pumping chamber, a pressure transfer chamber between said diaphragms, cylinder means between the diaphragms and in communication with the transfer chamber, liquid filling said transfer chamber and cylinder'means, one of said diaphragms-sealing the pumping chamber from the transfer chamber and the other the cylinder means from the motor means, reciprocating means driven by the motor means and operative to distort said other diaphragm toward the pumping chamber, piston means in said cylinder means in contact with said other diaphragm and adapted for reciprocation with said reciprocating means,

a liquid collection recess in the wall of said cylinder means adjacent said other diaphragm and adapted to collect liquid escaped from the transfer chamber, return conduit means interconnecting said collection recess and transfer chamber, and valve means in said conduit means adapted to-permit flow to the transfer chamber and to 1 I an.

chamber being of larger diameter than that more remote from the transfer chamber, and in which said piston means comprises a piston in each of said cylinders, said pistons being interconnected for conjoint reciprocation, said equipment further including a second liquid collection recess in the wall of the first mentioned cylinder, said second recess being located in the region of the interconnection between the first mentioned and second mentioned cylinders, said return conduit means interconnecting both of said recesses with the transfer chamber.

4. Pumping equipment according to claim 3 and furand a piston in said cylinder means in contact with said other diaphragm and adapted for reciprocation with said reciprocating means.

8. Pumping equipment according to claim 7 in which said reciprocating means comprises a ram driven by a cam.

9. Pumping equipment according to claim 7 and including resilient means urging the piston toward said reciprocating means.

10. Pumping equipment according to claim 7 and including a supporting screen located in the transfer chamber adjacent the first mentioned diaphragm.

11. A construction according to claim 10 in which the surface of said supporting screen adjacent the first mentioned diaphragm is composed of resilient material.

12: Pumping equipment according to claim 7 in which said reciprocating means comprises a crosshead driven by a connecting rod.

13. Pumping equipment according to claim 12 in which said other diaphragm is toroidal, the inner edge thereof being secured to said crosshead.

14. Pumping equipment according to claim 13 in which the crosshead reciprocates in a crossheadcylinder and further including a lubrication recess surrounding the phragms, liquid filling said hydraulic chamber, one ofsaid diaphragms sealing the 'pumping chamber from the hydraulic chamber and the other the hydraulic chamber from the motor means, reciprocating means driven by the motor means and operative to distort said other diaphragm toward the pumping chamber, the first mentioned diaphragm being arranged at an angle with respect to the horizontal, inlet and outlet valve means for said pumping chamber, the inlet and outlet valve means being arranged in the region of the highest and lowest points on the first mentioned diaphragm respectively.

16. Pumping equipment according to claim 15 in which the outlet valve means is arranged in-an outlet passage, the cross section of said outlet passage being hydrodynamically developed to provide a progressively increasing velocity of flow of liquid leaving the pumping chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,955,383 Hermann Apr. 17, 1934 FOREIGN PATENTS 597,106

Great Britain Jan. 19, 1948 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2,853,015 v September 23, 1958 Friedrich Wilhelm Pleuger It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below. 1

Column 1, line 18, for "upon" read up column 3, line 51, for "shown," read shown) column 5, line 15, for "39b" read 29b Signed and sealed this 20th day or January 1959.

Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

